diff --git a/README.md b/README.md
index fe1fd3b..2bf0356 100644
--- a/README.md
+++ b/README.md
@@ -7,12 +7,12 @@ This repository includes the necessary Python client libraries to access Hawkula
 
 ## Introduction
 
-Python client to access Hawkular-Metrics, an abstraction to invoke REST-methods on the server endpoint using urllib2. No external dependencies, works with Python 2.7.x (tested on 2.7.5/2.7.6 and 2.7.10/2.7.13) and Python 3.4.x / Python 3.5.x (tested with the Python 3.4.2 and Python 3.5.3, might work with newer versions also).
+Python client to access Hawkular-Metrics, an abstraction to invoke REST-methods on the server endpoint using urllib2. No external dependencies, works with Python 2.7.x (tested on 2.7.14) and Python 3.4.x / 3.5.x / 3.6.x (tested with the Python 3.4.2, Python 3.5.3 and Python 3.6.4, might work with newer versions also).
 
 ## License and copyright
 
 ```
-   Copyright 2015-2017 Red Hat, Inc. and/or its affiliates
+   Copyright 2015-2018 Red Hat, Inc. and/or its affiliates
    and other contributors.
 
    Licensed under the Apache License, Version 2.0 (the "License");
@@ -38,7 +38,7 @@ To use hawkular-client-python in your own program, after installation import fro
 
 The client provides a method to request current time in milliseconds, ``time_millis()`` that's accepted by the methods, but you can use ``datetime`` and ``timedelta`` to control the time also when sending requests to the Hawkular-Metrics. 
 
-See metrics_test.py for more detailed examples and [Hawkular-Metrics documentation](http://www.hawkular.org/docs/components/metrics/index.html) for more detailed explanation of available features.
+See ``tests/test_metrics.py`` for more detailed examples and [Hawkular-Metrics documentation](http://www.hawkular.org/hawkular-metrics/docs/user-guide/) for more detailed explanation of available features.
 
 ### General
 
diff --git a/hawkular/metrics.py b/hawkular/metrics.py
index ac18005..e50729b 100644
--- a/hawkular/metrics.py
+++ b/hawkular/metrics.py
@@ -177,12 +177,12 @@ def query_metric(self, metric_type, metric_id, start=None, end=None, **query_opt
                 self._get_metrics_single_url(metric_type, metric_id)),
             **query_options)
 
-    def query_metric_stats(self, metric_type, metric_id, start=None, end=None, bucketDuration=None, **query_options):
+    def query_metric_stats(self, metric_type, metric_id=None, start=None, end=None, bucketDuration=None, **query_options):
         """
         Query for metric aggregates from the server. This is called buckets in the Hawkular-Metrics documentation.
 
         :param metric_type: MetricType to be matched (required)
-        :param metric_id: Exact string matching metric id
+        :param metric_id: Exact string matching metric id or None for tags matching only
         :param start: Milliseconds since epoch or datetime instance
         :param end: Milliseconds since epoch or datetime instance
         :param bucketDuration: The timedelta or duration of buckets. Can be a string presentation or timedelta object
@@ -206,10 +206,14 @@ def query_metric_stats(self, metric_type, metric_id, start=None, end=None, bucke
             else:
                 query_options['bucketDuration'] = bucketDuration
 
-        return self._get(
-            self._get_metrics_stats_url(
-                self._get_metrics_single_url(metric_type, metric_id)),
-            **query_options)
+        if metric_id is not None:
+            url = self._get_metrics_stats_url(self._get_metrics_single_url(metric_type, metric_id))
+        else:
+            if len(query_options) < 0:
+                raise HawkularError('Tags are required when querying without metric_id')
+            url = self._get_metrics_stats_url(self._get_url(metric_type))
+
+        return self._get(url, **query_options)
 
     def query_metric_definition(self, metric_type, metric_id):
         """
diff --git a/tests/test_metrics.py b/tests/test_metrics.py
index bbea3ea..7cf1d60 100644
--- a/tests/test_metrics.py
+++ b/tests/test_metrics.py
@@ -306,6 +306,11 @@ def test_stats_queries(self):
         bp = self.client.query_metric_stats(MetricType.Gauge, 'test.buckets.1', bucketDuration=timedelta(seconds=2), start=now-timedelta(seconds=10), end=now, distinct=True)
         self.assertEqual(5, len(bp), "Single bucket is two seconds")
 
+        # Test previous metrics in a stacked configuration
+        stacks = self.client.query_metric_stats(MetricType.Gauge, buckets=1, tags=create_tags_filter(units='bytes', env='unittest'), percentiles=create_percentiles_filter(90.0, 99.0), stacked='true')
+        self.assertEqual(2.4, stacks[0]['min'], stacks)
+        self.assertEqual(15.45, stacks[0]['max'], stacks)
+
     def test_tenant_changing(self):
         self.client.create_metric_definition(MetricType.Availability, 'test.tenant.avail.1')
         # Fetch metrics and check that it did appear